Regulated aeration of gases exhausting through a propeller

Abstract

Aeration holes defined by an outer propeller hub include closure devices which seal the aeration holes during rotation of the propeller due to centrifugal forces in a predetermined speed of rotation range. The aeration holes provide high power at low boat speeds and are sealed at high boat speeds to avoid further aeration and loss of forward thrust. The speed of rotation at which the aeration hole are sealed is adjustable.

I claim: 
     
       1. A propeller comprising: an inner hub having an outermost wall,   an outer hub having an innermost wall, said outer hub being supported in spaced relation to and surrounding said inner hub,   an annular passageway defined between said outermost wall of said inner hub and said innermost wall of said outer hub,   a plurality of blades mounted on said outer hub,   a plurality of openings defined by said outer hub, each of said plurality of openings being located adjacent to a root of a leading edge of one of said plurality of blades,   reed valve means mounted in said annular passageway, said reed valve means including an elongated reed having a thickness substantially less than its length and width, said elongated reed being positioned in said annular passageway so that the restriction of gas flow through said annular passageway by the thickness of said elongated reed minimizes the blockages of gas flow through said annular passageway, said reed valve means being located adjacent each of said plurality of openings and biased away from each of said plurality of openings for moving towards each of said plurality of openings and at least partially sealing each of said plurality of openings due to centrifugal force acting against a bias of said reed valve means during rotation of the propeller in a predetermined speed range, said plurality of openings being substantially free of blockage by said reed valve means of gas flow through said openings outside of said predetermined spped range due to the bias of said reed valve means away from said plurality of openings, and   anticavitation means for allowing a small amount of gas to escape to an area adjacent to said plurality of blades when said reed valve means covers said plurality of openings.   
     
     
       2. A propeller as claimed in claim 1, wherein said reed valve means is mounted at one end on said inner hub. 
     
     
       3. A propeller as claimed in claim 1, wherein said reed valve means is mounted at one end on said outer hub. 
     
     
       4. A propeller as claimed in claim 1, wherein said reed valve means includes an adjusting means for adjusting the force required to cause said reed valve means to seal each of said plurality of openings. 
     
     
       5. A propeller comprising: an inner hub,   an outer hub supported in spaced relation to and surrounding said inner hub,   an annular passageway defined between said inner hub and said outer hub,   a plurality of blades mounted on said outer hub,   a plurality of openings defined by said outer hub, each of said plurality of openings being located adjacent to a root of a leading edge of one of said plurality of blades,   closure means mounted in said annular passageway adjacent each of said plurality of openings and biased away from each of said plurality of openings for movement towards each of said plurality of openings and sealing of each of said plurality of openings due to centrifugal force acting against the bias of said closure means during rotation of the propeller in a predetermined speed range, and   anticavitation means for allowing a small amount of gas to escape to an area adjacent to said plurality of blades when said closure means covers said plurality of openings.   
     
     
       6. A propeller comprising: a propeller hub having an inner hub and an outer hub supported in spaced relation to and surrounding said inner hub,   an annular passageway defined between said inner hub and said outer hub,   a plurality of blades mounted on said outer hub,   a plurality of openings defined by said outer hub, each of said plurality of openings being located adjacent to a root of a leading edge of one of said plurality of blades,   plate closure means for each of said plurality of openings, said plate closure means having two ends, one end being pivotably connected to said propeller hub and the other end adapted to seal each of said plurality of openings,   bias means for each of said plate closure means, said bias means having two ends, one end connected to said plate closure means and the other end being connected with said propeller hub, said plurality of openings being sealed by said plate closure means upon centrifugal force overcoming the bias of said bias means during rotation of the propeller in a predetermined speed range, and   stop means limiting the spacing of said plate closure means from said plurality of openings.   
     
     
       7. A propeller as claimed in claim 6, wherein said stop means project from said inner hub. 
     
     
       8. A propeller comprising: a propeller hub having an inner hub and an outer hub supported in spaced relation to and surrounding said inner hub,   an annular passageway defined between said inner hub and said outer hub,   a plurality of blades mounted on said outer hub,   a plurality of openings defined by said outer hub, each of said plurality of openings being located adjacent to a root of a leading edge of one of said plurality of blades,   plate closure means for each of said plurality of openings, said plate closure means having two ends, one end being pivotable connected to said propeller hub and the other end adapted to seal each of said plurality of openings,   bias means for each of said plate closure means, said bias means having two ends, one end connected to said plate closure means and the other end being connected with said propeller hub, said plurality of openings being sealed by said plate closure means upon centrifugal force overcoming the bias of said bias means during rotation of the propeller in a predetermined speed range, and   said one end of said bias means being positionable at different points along said outer hub to vary the tension of said bias means.   
     
     
       9. A propeller comprising: a propeller hub having an inner hub and an outer hub supported in spaced relation to and surrounding said inner hub,   an annular passageway defined between said inner hub and said outer hub,   a plurality of blades mounted on said outer hub,   a plurality of openings defined by said outer hub, each of said plurality of openings being located adjacent to a root of a leading edge of one of said plurality of blades,   plate closure means for each of said plurality of openings, said plate closure means having two ends, one end being pivotably connected to said propeller hub and the other end adapted to seal each of said plurality of openings,   bias means for each of said plate closure means, said bias means having two ends, one end connected to said plate closure means and the other end being connected with said propeller hub, said plurality of openings being sealed by said plate closure means upon centrifugal force overcoming the bias of said bias means during rotation of the propeller in a predetermined speed range, and   said one end of said bias means being positionable at different points along said inner hub to vary the tension of said bias means.